The invention relates generally to spherical-shaped semiconductor integrated circuit manufacturing and transportation processes, and more particularly, to a method and apparatus for contactless capturing and handling of spherical-shaped objects which is suitable for use in the manufacture and transport of spherical-shaped semiconductor integrated circuits.
Conventional integrated circuits, or "chips," are formed from a flat surface semiconductor wafer. The semiconductor wafer is first manufactured in a semiconductor material manufacturing facility and is then provided to a fabrication facility. At the latter facility, several layers are processed onto the semiconductor wafer surface. Once completed, the wafer is then cut into one or more chips and assembled into packages. Although the processed chip includes several layers fabricated thereon, the chip still remains relatively flat.
A fabrication facility is relatively expensive due to the enormous effort and expense required for creating flat silicon wafers and chips. For example, manufacturing the wafers requires several high-precision steps including creating rod-form polycrystalline semiconductor material; precisely cutting ingots from the semiconductor rods; cleaning and drying the cut ingots; manufacturing a large single crystal from the ingots by melting them in a quartz crucible; grinding, etching, and cleaning the surface of the crystal; cutting, lapping and polishing wafers from the crystal; and heat processing the wafers. Moreover, the wafers produced by the above processes typically have many defects which are largely attributable to the difficulty in making a single, highly pure crystal due to the above cutting, grinding and cleaning processes as well as due to the impurities, including oxygen, associated with containers used in forming the crystals. These defects become more and more prevalent as the integrated circuits formed on these wafers become smaller.
Another major problem associated with modern fabrication facilities for flat chips is that they require extensive and expensive equipment. For example, dust-free clean rooms and temperature-controlled manufacturing and storage areas are necessary to prevent the wafers and chips from defecting and warping. Also, these types of fabrication facilities suffer from a relatively inefficient throughput as well as an inefficient use of the silicon. For example, facilities using in-batch manufacturing, where the wafers are processed by lots, must maintain huge inventories to efficiently utilize all the equipment of the facility. Also, because the wafers are round, and the completed chips are rectangular, the peripheral portion of each wafer cannot be used.
Still another problem associated with modem fabrication facilities is that they do not produce chips that are ready to use. Instead, there are many additional steps that must be completed, including cutting and separating the chip from the wafer; assembling the chip to a lead frame which includes wire bonding, plastic or ceramic molding and cutting and forming the leads, positioning the assembled chip onto a printed circuit board; and mounting the assembled chip to the printed circuit board. The cutting and assembly steps introduce many-errors and defects due to the precise requirements of such operations. In addition, the positioning and mounting steps are naturally two-dimensional in character, and therefore do not support curved or three dimensional areas.
Therefore, due to these and various other problems, only a few companies in the world today can successfully manufacture conventional flat chips. Furthermore, the chips must bear a high price to cover the costs of manufacturing, as well as the return on initial capital and investment.
In co-pending U.S. patent application Ser. No. 08/858,004 filed on May 16, 1997, now U.S. Pat. No. 5,955,776 issued Sep. 21, 1999 assigned to the same assignee as the present application and hereby incorporated by reference as if reproduced in its entirety, a method and apparatus for manufacturing spherical-shaped semiconductor integrated circuits is disclosed. As disclosed in the aforementioned patent application, the manufacturing process by which a spherical-shaped semiconductor integrated circuit is produced may include a variety of processing steps. Among these are: de-ionized water cleaning, developing and wet etching; diffusion, oxidation and deposition of films; coating; exposure; plasma etching, sputtering and ion implantation; ashing; and epitaxial growth.
Complicating the manufacturing process for spherical-shaped semiconductor integrated circuits are the special handling requirements which must be afforded the circuits during the manufacture thereof. Unlike conventional integrated circuits formed from flat surface semiconductor wafers, the spherical-shaped semiconductor integrated circuits produced from spherical-shaped semiconductors consume the entire surface area of the spherical-shaped semiconductors. Thus, unlike conventional integrated circuits which may be grasped along bottom or side surfaces thereof, grasping or otherwise contacting spherical-shaped semiconductor during the manufacturing process may result in significant damage thereto. Thus, many of the processing techniques used to manufacture conventional integrated circuits are unsuitable for use in the manufacture of spherical-shaped semiconductor integrated circuits.
Thus, the difficulties associated with the handling and transport of spherical-shaped semiconductor integrated circuits during the manufacturing process remains an obstacle to the development of such devices. Much of the attention in solving this problem has focussed, however, on how to transport spherical-shaped semiconductors between adjacent process stations in a spherical-shaped semiconductor integrated circuit manufacturing system. Typically, such manufacturing systems include one or more transport tubes specially designed to carry spherical-shaped semiconductors between process stations while preventing the spherical-shaped semiconductors from contacting the sidewalls of the tubes, typically using flow control techniques such as those disclosed in co-pending U.S. patent application Ser. No. 08/858,004, now U.S. Pat. No. 5,955,766, and previously incorporated by reference into the present application.
Such transport tubes are typically sealed systems for transporting large volumes of spherical-shaped semiconductors between process stations. Thus, there remains a need, however, for a device capable of contactless capturing, holding and transporting of spherical-shaped semiconductors. Such a device would be particularly useful if configured as a hand-held device. For example, such a device could be used to remove selected spherical-shaped semiconductors from a spherical-shaped semiconductor integrated circuit manufacturing process for examination, testing or manual transport between processing stations. In the past, either mechanical tweezers or various types of vacuum devices were used to capture and transport spherical-shaped semiconductors. However, these devices all relied upon physical contact to capture the spherical-shaped semiconductors. As a result, the surface of the spherical-shaped semiconductors were often damaged during capture and transport operations.
While the levitation of spherical-shaped objects has been disclosed, such levitation devices are not particularly well suited for performing capture and transport operations. For example, U.S. Pat. No. 4,378,209 to Berge et al. discloses a gas levitator capable of levitating a specimen of material in a containerless environment. The levitator disclosed in Berge et al. is, however, characterized by an elongated downstream section which renders it difficult, if not impossible to use Berge et al. outside of the disclosed use as a processing station for the levitated specimen.
Thus, there remains a need for a device capable of readily capturing, holding and transporting spherical-shaped objects, particularly, if the device is capable of being operated as a stand-alone and/or hand-held tool. It is, therefore, the object of the invention to provide such a tool.